docs: def map(self, key, value):
          """
          Args:
              key: Image name
              value: Image as jpeg byte data
  
          Yields:
              A tuple in the form of (key, value)
              key: Constant dummy value
              value: (l2sqr_dist, value)
          """
          try:
              image = imfeat.resize_image(imfeat.image_fromstring(value, {'type': 'numpy', 'mode': 'bgr', 'dtype': 'uint8'}),
                                          100, 100)
          except:
              hadoopy.counter('DATA_ERRORS', 'ImageLoadError')
              return
  
          # Distance metric
          diff = image - self.target_image
          dist = np.sum(diff * diff)
  
          # Output
          if dist < self.min_dist:
              self.min_dist = dist
              self.min_key = key
              self.min_value = value